Colloquium

Displaying 373 - 384 of 614

Electronic Liquid Crystalline Phases of Highly Correlated Electronic Systems
April 24, 2013

PIRSA:13040116
Condensed Matter
Energy and the Environment - What Physicists Can Do

John Baez University of California, Riverside
April 17, 2013

PIRSA:13040030
Mathematical physics
Black holes as probes of fundamental physics

Vitor Cardoso Instituto Superior Tecnico - Departamento de Física
April 03, 2013

PIRSA:13040109
Particle Physics

Cosmology
Quoins versus Coins

Terry Rudolph Imperial College London
March 27, 2013

PIRSA:13030000
Quantum Information
Supersymmetric gauge theory and the Yangian - continued

Kevin Costello Perimeter Institute for Theoretical Physics

March 26, 2013

PIRSA:13030115
Dissecting holography with higher spins

Xi Yin Harvard University
March 25, 2013

PIRSA:13030098
Quantum Fields and Strings
Supersymmetric gauge theory and the Yangian

Kevin Costello Perimeter Institute for Theoretical Physics

March 25, 2013

PIRSA:13030114
Frustrated Magnets and Quantum Spin Liquids

Steven White University of California, Irvine
March 20, 2013

PIRSA:13030097
Condensed Matter
The Higgs confronts 3 universes at the LHC

Markus Luty University of California, Davis
March 13, 2013

PIRSA:13030095
Particle Physics
Rethinking Cosmology
March 06, 2013

PIRSA:13030079
Cosmology
Non-perturbative problems in gauge theories: N=2 quiver QCD

Vasily Pestun Institute for Advanced Study (IAS)
March 06, 2013

PIRSA:13030103
Quantum Fields and Strings
Getting the Most out of a Black Hole

Alexander Tchekhovskoy Princeton University
March 04, 2013

PIRSA:13030102
Cosmology

Electronic Liquid Crystalline Phases of Highly Correlated Electronic Systems
April 24, 2013

PIRSA:13040116
Condensed Matter
In one extreme, where the interactions are sufficiently weak compared to the interactions, electrons form a “Fermi liquid” – the state that accounts for the properties of simple metals. In the other extreme, where the interactions are dominant, the electrons form various “Mott” insulating or “Wigner crystalline” phases, often characterized by broken spatial and/or magnetic symmetries. Corresponding charge and/or magnetically ordered insulating phases are common in nature. Between these two extremes lie highly correlated electronic fluids, and correspondingly a host of interesting and perplexing materials, including such diverse systems as the cuprate and iron-based high temperature superconductors, the failed metamagnet Sr3Ru2O7, and a variety of quantum Hall fluids. Some insight into electron fluids in this rich intermediate coupling regime can be obtained from viewing them as partially melted electron solids, rather than as strongly interacting gases. Here, analogies with the liquid crystalline phases of complex classical fluids provide useful guidance for a new approach to this key problem in condensed matter physics.
Energy and the Environment - What Physicists Can Do

John Baez University of California, Riverside
April 17, 2013

PIRSA:13040030
Mathematical physics
The global warming crisis is part of a bigger transformation in which humanity realizes that the Earth is a finite system and that our population, energy usage, and the like cannot continue to grow exponentially. While politics and economics pose the biggest challenges, physicists are in a good position to help make this transition a bit easier. After a quick review of the problems, we discuss a few ways physicists can help.
Black holes as probes of fundamental physics

Vitor Cardoso Instituto Superior Tecnico - Departamento de Física
April 03, 2013

PIRSA:13040109
Particle Physics

Cosmology
Black holes are the elementary particles of gravity, the final state of sufficiently massive stars and of energetic collisions. With a forty-year long history, black hole physics is a fully-blossomed field which promises to embrace several branches of theoretical physics. Here I review the main developments in highly dynamical black holes with an emphasis on high energy black hole collisions and probes of particle physics via superradiance.
Quoins versus Coins

Terry Rudolph Imperial College London
March 27, 2013

PIRSA:13030000
Quantum Information
Human monkeys are used to thinking about the problem of choosing from a set of objects according to some desired, biased, probability distribution. Just think about how you chose your partner(s). Even when it is easy for you to do such a sampling, it can be difficult to do a quantum sampling (Q-Sampling) of the same distribution. By Q-Sampling I mean the creation of a coherent superposition of states of such objects whose amplitudes are the (square roots of) of the specified distribution. In this talk I will discuss what we do know about this problem, why it is interesting, and will discuss how it can let us achieve tasks with quantum information that are provably impossible classically.
Supersymmetric gauge theory and the Yangian - continued

Kevin Costello Perimeter Institute for Theoretical Physics

March 26, 2013

PIRSA:13030115

I'll explain a new connection between supersymmetric gauge theories and the Yangian. The main result is that a twisted, deformed version of the pure N=1 supersymmetric gauge theory is controlled by the Yangian, in the same way that Chern-Simons theory is controlled by the quantum group. This result is used to give an exact calculation, in perturbation theory, of the expectation value of a certain net of n+m Wilson operators in the deformed N=1 gauge theory. This expectation value coincides with the partition function of a spin-chain integrable lattice model on an n-by-m doubly-periodic lattice.
Dissecting holography with higher spins

Xi Yin Harvard University
March 25, 2013

PIRSA:13030098
Quantum Fields and Strings
The holographic correspondence is a powerful duality between a quantum theory of gravity and a quantum gauge theory in one lower space-time dimension. Higher spin gravity theories, i.e. gravity theories that also contain (gauge) fields of spins greater than 2, play a special role in holography. I will explain consistent interacting higher spin gravity theories in anti-de Sitter space, their duality with gauged conformal vector models, and their connection to string theory.
Supersymmetric gauge theory and the Yangian

Kevin Costello Perimeter Institute for Theoretical Physics

March 25, 2013

PIRSA:13030114

I'll explain a new connection between supersymmetric gauge theories and the Yangian. The main result is that a twisted, deformed version of the pure N=1 supersymmetric gauge theory is controlled by the Yangian, in the same way that Chern-Simons theory is controlled by the quantum group. This result is used to give an exact calculation, in perturbation theory, of the expectation value of a certain net of n+m Wilson operators in the deformed N=1 gauge theory. This expectation value coincides with the partition function of a spin-chain integrable lattice model on an n-by-m doubly-periodic lattice.
Frustrated Magnets and Quantum Spin Liquids

Steven White University of California, Irvine
March 20, 2013

PIRSA:13030097
Condensed Matter
A quantum spin liquid is a solid whose atoms have magnetic moments but, because of quantum fluctuations, these moments fluctuate like a liquid even at zero temperature. Two dimensional spin liquids have been suggested as a way to produce high temperature superconductivity, and to build quantum computers. Just as helium is the only element which is a liquid at zero temperature, 2D spin liquids have been extremely difficult to find, despite decades of effort, raising the question, do realistic spin liquids even exist?
Recently, apparent spin liquids have been found experimentally, stimulating theoretical work to find simple model Hamiltonians of frustrated spin systems that have spin liquid ground states.

In this talk, I will give a broad overview of spin liquids and then focus on our simulations of the kagome Heisenberg model, a simple, realistic model of some of the recent experimental spin liquids, where we find a spin liquid ground state.
The Higgs confronts 3 universes at the LHC

Markus Luty University of California, Davis
March 13, 2013

PIRSA:13030095
Particle Physics
The recent discovery of the Higgs boson is a fundamental advance in particle physics. This talk gives a theorist's perspective of the significance of this discovery. The Higgs boson was proposed in the 1960s, but it is best understood in the context of the quest to understand the weak interactions, which began with Fermi's theory of weak interactions almost 80 years ago. This has led to three very different paradigms for the structure of fundamental interactions at the TeV scale: supersymmetry, compositeness/extra dimensions, and anthropic selection. The Large Hadron Collider is the experimentum crucis for deciding between these different possible universes, and the discovery of the Higgs is a crucial clue. This talk will describe these paradigms, the implications of the Higgs discovery for them, and the outlook for further discoveries that would decide between them.
Rethinking Cosmology
March 06, 2013

PIRSA:13030079
Cosmology
This talk will begin by discussing one by one the various reasons why cosmologists today consider the big bang inflationary cosmology to be the leading, if not proven, theory of the universe and then explaining why each of these reasons is flawed. This leads naturally to the question: what is the alternative? Understanding the flaws helps point the way.
Non-perturbative problems in gauge theories: N=2 quiver QCD

Vasily Pestun Institute for Advanced Study (IAS)
March 06, 2013

PIRSA:13030103
Quantum Fields and Strings
Non-perturbative effects are responsible for the essential dynamical features of the four-dimensional gauge theories such as QCD. The N=2 supersymmetric four-dimensional theories are an interesting class of models in which non-perturbative computations can be carried out with arbitrary precision using localization of the path integrals. I will explain the new exact non-perturbative results and the relation to classical and quantum integrable systems for a large class of N=2 supersymmetric QCD.
Getting the Most out of a Black Hole

Alexander Tchekhovskoy Princeton University
March 04, 2013

PIRSA:13030102
Cosmology
As black holes accrete surrounding gas, they often produce relativistic, collimated outflows, or jets. Jets are expected to form in the black hole vicinity making them powerful probes of strong-field gravity. However, how jet properties are connected to black hole and accretion flow properties has been unclear. Recent progress in computer simulations of black hole accretion enables studies of jet formation in unprecedented detail. For the first time, 3D general relativistic magnetohydrodynamic numerical simulations allow one to determine the maximum efficiency with which accretion onto black holes can power relativistic jets. I will present the dependence of this maximum efficiency on black hole spin and discuss how this dependence allows one to probe strong-field gravity. In realistic astrophysical systems, the angular momentum vector of the accretion flow can be tilted relative to the spin of the black hole. I will present the first simulations of jets from such tilted accretion systems and discuss their observational signatures.

Title	Speaker(s)	Date	Talk Type	Info
Electronic Liquid Crystalline Phases of Highly Correlated Electronic Systems		2013-04-24	Scientific Series	View details
Energy and the Environment - What Physicists Can Do	John Baez	2013-04-17	Scientific Series	View details
Black holes as probes of fundamental physics	Vitor Cardoso	2013-04-03	Scientific Series	View details
Quoins versus Coins	Terry Rudolph	2013-03-27	Scientific Series	View details
Supersymmetric gauge theory and the Yangian - continued	Kevin Costello	2013-03-26	Scientific Series	View details
Dissecting holography with higher spins	Xi Yin	2013-03-25	Scientific Series	View details
Supersymmetric gauge theory and the Yangian	Kevin Costello	2013-03-25	Scientific Series	View details
Frustrated Magnets and Quantum Spin Liquids	Steven White	2013-03-20	Scientific Series	View details
The Higgs confronts 3 universes at the LHC	Markus Luty	2013-03-13	Scientific Series	View details
Rethinking Cosmology		2013-03-06	Scientific Series	View details
Non-perturbative problems in gauge theories: N=2 quiver QCD	Vasily Pestun	2013-03-06	Scientific Series	View details
Getting the Most out of a Black Hole	Alexander Tchekhovskoy	2013-03-04	Scientific Series	View details

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